Non-Rotating CMP Stage With Multi-Actuator Film Thickness Control
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Solution Overview
Problem
Existing chemical mechanical polishing (CMP) technologies face challenges in achieving precise control of film thickness variation to the order of several nanometers over the entire surface of a wafer, particularly due to the complexity of connecting power lines to rotary connectors and the need for small-diameter polishing pads that prolong polishing time.
Innovation Solution
A non-rotating polishing apparatus with a stage that holds the substrate facing upward, utilizing a plurality of pressing actuators and a rotating polishing pad to control film thickness through independent pressing and spiral trajectories, along with film thickness measuring devices and a simplified control line system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polishing pad with a small diameter is used to control pressure for each small area on the wafer, then film thickness profile control precision is improved, but polishing time increases
Solution Approach 1:
The polishing head is divided into multiple independent pressing actuators (first, second, third pressing actuators) that can independently adjust pressure on different regions of the wafer. This segmentation allows precise local pressure control without requiring a small polishing pad, thereby maintaining high film thickness profile control precision while enabling the use of a larger polishing pad to reduce polishing time.
2Adaptability or versatility
If all power lines are connected to a rotary connector to enable rotation of the polishing head, then polishing head rotation capability is improved, but device complexity increases
Solution Approach 1:
Instead of rotating the polishing head (which would require complex rotary connectors for power line transmission), the invention inverts the approach by keeping the polishing head stationary and rotating the wafer on the polishing apparatus. This eliminates the need for rotary connectors while maintaining the ability to perform rotational polishing, thereby reducing device complexity while preserving polishing head rotation capability.
3Device complexity
If a non-rotating polishing apparatus is used to simplify the structure, then device complexity is reduced, but film thickness control precision may be compromised
Solution Approach 1:
The invention introduces dynamic pressure control through multiple independently controllable pressing actuators that can adjust their pressing forces in real-time. This dynamic adjustment capability allows the stationary polishing head to achieve precise film thickness control by varying pressure distribution across different wafer regions, compensating for the lack of physical rotation while maintaining high manufacturing precision.
Solution Approach 2:
The polishing apparatus incorporates film thickness measurement capabilities that provide feedback to the control system. This feedback enables the pressing actuators to dynamically adjust their forces based on actual film thickness measurements, ensuring precise film thickness control even in a non-rotating configuration. The feedback mechanism allows the system to compensate for any precision losses that might result from the simplified structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus achieves high-accuracy film thickness control with a simplified structure by eliminating the need for rotary connectors and enabling precise polishing through adjustable pressing forces and spiral trajectories.
Implementation Method 1
a plurality of pressing actuators arranged inside the stage, and configured to independently press a specific portion of the substrate
Implementation Method 2
a polishing-pad rotating mechanism configured to rotate the polishing pad about its own center
Implementation Method 3
a film thickness measuring device configured to detect a film thickness signal corresponding to a film thickness of the substrate
Data Source
AI summary
A polishing apparatus that are simple in structure and capable of controlling a film thickness profile of a substrate with high accuracy is disclosed. The polishing apparatus includes a stage configured to hold the substrate and having a non-rotating structure, a plurality of pressing actuators, a pad holder, and a polishing-pad rotating mechanism.